Solar photovoltaic modules of solar arrays may suffer from mismatch conditions relative to each other because of one or more of the following mechanisms. A solar array is made up of one or more modules, and the modules may be connected together in one or more strings within the array. Varying shadowing with varying intensity may exist on different parts of the solar array in actual installations. Temperatures may have non-uniform distributions across the solar array. Debris, such as bird droppings, particular accumulation due to dust and other pollutants may soil the panels in a non-uniform manner. Manufacturing processes may result in variations across panels and the panels may age differently.
In traditional systems, where each of the solar modules in a string is connected in series, such mismatches lead to degraded performance of total energy harvest. In a typical environment, it has been demonstrated that such shadowing and mismatch related issues lead to up to 25% of lost energy. Recently, various technologies have been developed to solve these problems. In particular, Microinverter and Power Optimizer technologies improve the system performance by embedding electronics close to each of the solar panels. In the case of microinverters, the energy harvested from the individual solar module is converted to AC, which is suitable for directly feeding into the power system grid. In case of the power optimizer, each of the solar modules consists of a DC-DC converter. The outputs of the DC-DC converters are then connected in series to form solar strings, which are then fed into a centralized inverter for converting to AC suitable for feeding into the grid.
In either case of the microinverters or power optimizers, the individual solar modules are decoupled from each other, and are operated at their maximum power point allowing maximum possible energy harvest. Each of the solar modules in this event can have their individual maximum power point due to their own individual operating condition specific to the extent to which the solar module is soiled or shadowed. Irrespective of the implementation of these technologies, soiled arrays continue to perform sub-optimally with respect to the un-soiled arrays.
Certain shadows and their movements over the year are sometimes pre-known during design and installation due to static structural elements surrounding the arrays. However, in a majority of the situations the shadowing elements are semi-static. Some examples include shadowing due to various factors such as growing trees, slow accumulation of dust or particulate pollutants, random non-uniform bird droppings, and falling debris. Resolution of the majority of the semi-static shadowing requires a variety of service crews to physically reach the array and perform the required maintenance.
Depending on the type of shadowing mechanism, the service crew needed can be different. For example, a growing tree must be cut by a certified landscaping professional, versus particulate accumulation on the solar arrays that must be removed by solar panel cleaning services. The former can be performed without ever touching the arrays, thus the service crew need not have certification and/or knowledge to complete the service. However, the latter needs physically accessing the arrays, and thus may need to be performed by a crew having at least the operational know-how and safety issues of the solar arrays. In such situations, one can anticipate different cost structure associated with different types of service requests. Thus, it becomes imperative to cost effectively and preferably automatically determine if a service request is required, and if required, determine the type of the service request so that appropriate service professional can be sent.